I don't have the Helix but I do have a Line 6 HD500 which is a few generations behind and a similar concept.
I also have 3 of the Eventide stomp boxes, the H9 Max, and a lexicon MX400.
My impression is they are not the same thing.
The Line 6 gives you a whole set of effects mainly modelled on classic stomp boxes. You can have several running at once and you can arrange them in different ways. Being mainly for guitars (It'll accept Line level as well) there's also umpteen different amp and speaker emulations.
You can set up some pretty sophisticated effects chains for some weird and whacky sounds. You can also emulate things, I put a string machine through it and it absolutely nailed a JMJ sound from Oxygene.
The Eventide stomp boxes are completely different. They concentrate on giving you one big "character" effect at a time.
The quality of the effects are indisputable but you pay for them. The HD500 cost about the same as one of the Eventide stomp boxes.
For the Lexicon I got it ages ago and hooked it up to my mixer. It's sat there and been used on everything ever since. The effects aren't as characterful as the Eventide but sometimes you just need to add some non-intrusive reverb or chorus and the Lexicon is good at that. You can also add a great big reverb on something if you want to, it's pretty good at that too.
FX are a bit like synths, they're all useful but they're good at different things. They also quite personal, some people really don't seem to like the character the Eventide stuff give you. The Eventide effects definitely put an imprint in a sound, when I was going through the H9 algorithms I recognised them from music I've heard! I don't think that's a problem but YMMV.
OTOH the power of the Eventide stuff can be very useful. The Korg Minilogue doesn't have quite the oomph of some of my other synths. Put it through the chorus-reverb algorithm and this is no longer a problem!